Myeloid-cell differentiation redefined in cancer

Abstract

The differentiation of monocytes is altered in cancer, which results in the unexpected conversion of a large proportion of monocytic myeloid-derived suppressor cells into polymorphonuclear myeloid-derived suppressor cells.

Figure 1

M-MDSCs differentiate into PMN-MDSCs in tumor-bearing hosts. Soluble mediators produced in the tumor microenvironment promote the aberrant differentiation of MDSCs. Dashed lines indicate the normal developmental pathway of immature myeloid precursor cells, which differentiate into DCs, monocytes-macrophages and granulocytes (basophils, eosinophils and neutrophils) in non-tumor-bearing hosts. Solid lines indicate the aberrant pathways of myeloid cell development in tumor-bearing hosts. New data (thick red line) suggest that a large proportion of PMN-MDSCs emerge from the M-MDSC pool. HSC, hematopoietic stem cell; TAM, tumor-associated macrophage.